Natural Gas, a Non-renewable Resource
Natural gas is presently used in many types of vehicles in Italy, the former Soviet Union, New Zealand, Australia, Canada, Argentina, and the United States. Compressed Natural Gas is used in vehicles of all weights and sizes; CNG fueling stations are located in most major cities where pipelines exist from major Natural Gas Utility Companies. In urban areas, typically a CNG compressor compresses the gas from the utility company into a large holding tank at 3,600 pounds per square inch (psi) for dispensing into motor vehicle fuel tanks.
In many rural areas, where pipelines do not exist, Liquefied Natural Gas (LNG) is trucked or distributed via rail to refueling stations. Primarily large trucks, locomotives, and transit buses use it.
Many taxi cabs and airport shuttle passenger vans operate on CNG because they help reduce pollution around airports. For example, major airports such as in Los Angeles and Phoenix require cabs and shuttle buses to operate on clean burning fuels. Natural gas is the fuel of choice for operation of these vehicles because of the refueling availability.
Some vehicles also operate on CNG or gasoline, not as a blend, but one fuel or the other. These vehicles, called bi-fuel or dual-fuel vehicles, can manually be switched between natural gas or gasoline, or if operation on natural gas is not possible because of low fuel/low pressure, the engine will automatically switch over to gasoline with out engine stall or hesitation. These vehicles have both natural gas and gasoline tanks on-board. Ford first introduced these vehicles commercially in 1996. GM and other major automakers have since followed.